﻿<!DOCTYPE html>
<html lang="en">
<head>
    <title>内嵌函数的使用</title>
</head>
<body>
    <p>局部变量计数</p>
    <p id="demo">0</p>
    <script>
        document.getElementById("demo").innerHTML = add();
        function add() {
            let counter = 0;
            function plus() { 
                counter += 1; 
            }
            plus();
            return counter;
        }
    </script>
</body>
</html>
